Applying reinforcement learning (RL) to real-world problems is often made challenging by the inability to interact with the environment and the difficulty of designing reward functions. Offline RL addresses the first challenge by considering access to an offline dataset of environment interactions labeled by the reward function. In contrast, Preference-based RL does not assume access to the reward function and learns it from preferences, but typically requires an online interaction with the environment. We bridge the gap between these frameworks by exploring efficient methods for acquiring preference feedback in a fully offline setup. We propose Sim-OPRL, an offline preference-based reinforcement learning algorithm, which leverages a learned environment model to elicit preference feedback on simulated rollouts. Drawing on insights from both the offline RL and the preference-based RL literature, our algorithm employs a pessimistic approach for out-of-distribution data, and an optimistic approach for acquiring informative preferences about the optimal policy. We provide theoretical guarantees regarding the sample complexity of our approach, dependent on how well the offline data covers the optimal policy. Finally, we demonstrate the empirical performance of Sim-OPRL in different environments.

利用学习到的环境模型，在完全离线的环境中提出了一种离线基于偏好的强化学习算法Sim-OPRL，通过模拟轨迹获取偏好反馈，对于超出分布的数据采用悲观方法，对于获取最优策略相关的信息采用乐观方法，提供了关于样本复杂度的理论保证，最后通过在不同环境中的实验结果展示了Sim-OPRL的经验性能。

离线强化学习的偏好调查